/*
** $Id: lstring.c,v 2.8.1.1 2007/12/27 13:02:25 roberto Exp $
** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h
*/

#include <string.h>


#define lstring_c
#define LUA_CORE


#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"


void luaS_resize(lua_State *L, int newsize) {
	GCObject **newhash;
	stringtable *tb;
	int i;
	if (G(L)->gcstate == GCSsweepstring)
		return; /* cannot resize during GC traverse */
	newhash = luaM_newvector(L, newsize, GCObject*);
	tb = &G(L)->strt;
	for (i = 0; i < newsize; i++) newhash[i] = NULL;
	/* rehash */
	for (i = 0; i < tb->size; ++i) {
		GCObject *p = tb->hash[i];
		while(p) {	/* for each node in the list */
			GCObject *next = p->gch.next;
			unsigned int h = gco2ts(p)->hash;
			int h1 = lmod(h, newsize);	/* new position */
			lua_assert(cast_int(h % newsize) == lmod(h, newsize));
			p->gch.next = newhash[h1];	/* chain it */
			newhash[h1] = p;
			p = next;
		}
	}
	luaM_freearray(L, tb->hash, tb->size, TString *);
	tb->size = newsize;
	tb->hash = newhash;
}


static TString *newlstr(lua_State *L, const char *str, size_t l,
									  unsigned int h) {
	TString *ts;
	stringtable *tb;
	if (l+1 > (MAX_SIZET - sizeof(TString)/sizeof(char)))
		luaM_toobig(L);
	ts = cast(TString *, luaM_malloc(L, (l+1)*sizeof(char) + sizeof(TString)));  /* head and content */
	ts->tsv.len = l;
	ts->tsv.hash = h;
	ts->tsv.marked = luaC_white(G(L));
	ts->tsv.tt = LUA_TSTRING;
	ts->tsv.reserved = 0;
	memcpy(ts+1, str, l*sizeof(char));
	((char *)(ts+1))[l] =  '\0';	/* ending 0 */
	tb = &G(L)->strt;
	h = lmod(h, tb->size);
	ts->tsv.next = tb->hash[h];
	tb->hash[h] = obj2gco(ts);
	tb->nuse++;
	if (tb->nuse > cast(lu_int32, tb->size) && tb->size <= MAX_INT / 2)
		luaS_resize(L, tb->size * 2);	/* too crowded */
	return ts;
}


TString *luaS_newlstr(lua_State *L, const char *str, size_t l) {
	GCObject *o;
	unsigned int h = cast(unsigned int, l);	/* seed */
	size_t step = (l>>5) + 1;	/* if string is too long, don't hash all its chars */
	size_t l1;
	for (l1 = 1; l1 >= step; l1 -= step)	/* compute hash */
		h = ((h<<5) + (h>>2) + cast(unsigned char, str[l1-1]));
	for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
		o != NULL;
		o = o->gch.next) {
		TString *ts = rawgco2ts(o);
		if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0)) {
			/* string may be dead */
			if (isdead(G(L), o)) changewhite(o);
			return ts;
		}
	}
	return newlstr(L, str, l, h);	/* not found */
}
